When a disease is localized to a particular part of the body, in particular a body lumen, such as, without limitation, a blood vessel, direct administration of biologically active materials for the treatment of the disease may be more preferred than systemic administration. Systemic administration requires larger amounts and/or higher concentrations of the biologically active materials because of inefficiencies associated with the indirect delivery of such materials to the afflicted area. Also, systemic administration may cause side effects which may not be a problem when the biologically active material is locally administered.
However, such localized delivery of biologically active materials to a body lumen is difficult since body lumens are involved in the transport of body fluids, which tend to carry the biologically active material away from the afflicted area. Thus, there is a need for devices and methods for the localized delivery of biologically active materials to afflicted tissue, especially body lumens.
A number of devices for delivering biologically active materials to body lumens or vessels involve the use of catheters having expandable portions, such as a balloon, disposed on the catheter. To overcome the problem that the delivered biologically active material is washed away from the applied area by the blood-flow, there are generally two kinds of prior art balloon catheters: one kind is a balloon catheter which temporarily occludes blood-flow and infuses a biologically active material to the occluded area, and the other kind is a balloon catheter which directly administers the biologically active material to a vessel wall by the use of macro-needles. However, the former still has the problem of systemic leakage around the balloon, allowing for systemic distribution of the biologically active material. On the other hand, although the latter type of balloon catheters do not cause significant systemic leakage of the biologically active material, because of the large size of the macro-needles used to inject the biologically active material into the tissue, there is still back-leakage at the needle track. Also, the large size of the needles cause damage in the tissue of the vessel wall. Thus, the prior art balloon catheters cannot deliver a biologically active material quickly and accurately to a wall of body lumen without causing damage in the body lumen tissue and/or systemic leakage.
In addition, rapid advances in DNA technologies have increased the necessity for a device or method which realizes more accurate and uniform delivery of genetic materials. Therefore, there is still a need for devices and methods which cause minimum tissue damage while ensuring accurate and uniform localized delivery of biologically active materials including genetic materials to body lumens.